Last night's National Symphony Orchestra concert sounded a bit anticlimactic after the opening number -- not because the rest of the program lacked interest but because the evening began with the world premiere of Rodion Shchedrin's "Stykhira."

Although "Stykhira" (a Russian title meaning "Liturgical Hymn") was striking, the impact of the occasion went far beyond musical values. The new work, which arrived unexpectedly from the Soviet Union a few weeks ago, was composed by the secretary of the Composers' Union, the second most powerful musician in the U.S.S.R.

It is dedicated to NSO conductor Mstislav Rostropovich -- the first work by a major Soviet composer to bear such a dedication since 1974, when Rostropovich and his family went into exile and became "nonpersons." And it treats a religious theme ("The Millennium of the Baptism of Russia") with reverence, odd in a nation whose government has been officially, often militantly atheist for several generations.

There is no reason at all to doubt that Shchedrin's composition of this "unorthodox" work and his gestures of friendship toward a persona who has been non grata for more than a dozen years were done with the full knowledge and consent of the Soviet government. Thus, the political interest of this 14-minute work may outweigh its musical interest in many minds.

Not that the musical interest is low. "Stykhira" proved to be better in some ways than at least two of the already established pieces performed last night. It is more tightly organized and unified in its impact than Prokofiev's "Russian" Overture, a work of similar length, structures and orientation, which concluded the program. And it has more color and energy than Glazunov's Violin Concerto in A Minor, the first of two concertos played by Anne-Sophie Mutter. It is not better music than Prokofiev's Violin Concerto No. 1, which Mutter also played, but it had more impact last night because it seemed more thoroughly prepared.

"Stykhira" is a series of broad, colorful gestures, attractively melodious, artfully evocative, orchestrated with power and clarity and structured with a good sense of climax. It plumbs no great depths, but that is not its function. It is essentially declamatory, and it works well on that level.

It opens with a very striking idea that is also a graceful compliment to Rostropovich and the NSO. The cello section (which Rostropovich has described as the world's best) introduces the main theme, a simple, plainchant melody that is both Russian and religious in flavor. The cellists not only play the melody (beginning very softly and gradually raising the volume); they also hum along, and suddenly the cellists are transformed, aurally, into a group of monks chanting wordless prayers in an imaginary chapel.

The melody comes back at the end, with the cellists humming again, but meanwhile it is handed on from one section of the orchestra to another, with some very striking sounds produced, in turn, by the brass, percussion and violins. The sound of bells (rich with religious overtones) is prominent in the percussion. A set of large bells was brought in from Pennsylvania, where Schulmerich Carillons Inc. temporarily dismantled one of its carillons to make orchestral instruments.

There is probably a subliminal program for the music, though none was announced. For example, the transformations of the music could portray the vicissitudes that have affected Christianity since it was adopted in Kiev a millennium ago: wars, social upheaval, revolution and industrialization, perhaps, with the return of the humming chorus indicating that the Christian spirit remains unchanged. Or the structure could indicate the way Christianity was accepted by the nations that constitute the Soviet Union (some, not all) after first taking root in the Ukraine.

Or the music could be far from either of these meanings; we are dealing here with the essential ambiguity of instrumental music, a factor that enhances its longevity and helps it to communicate across enormous cultural barriers. Shchedrin's music does that; and, in a sense, that kind of communication is what it is about.

Substantial parts of this concert are scheduled for recording by Erato Records. On opening night, both violin concertos sounded as if they could use adjustments before being recorded. Mutter began rather unsteadily, with her E-string sounding weak and out of balance compared with the rich, gutsy tone of her G-string. Her cadenza in the Glazunov was magnificent, but once or twice she seemed to have trouble coordinating with the orchestra. She was better in the Prokofiev but some of the music could have been attacked with more vigor.

Nine members of the orchestra performed two pieces of baroque chamber music, by Telemann and Hertel, in a stylishly played "Prelude Concert."